ASME Materials

[chris456s]

I have been reading posts regarding an issue I commonly encounter.
How to use API-5L pipe or ASTM A694 flanges with ASME codes when ASME VIII and II does not list them?
Often the answer is that the ASME just doesn't cover these materials and you can use unlisted stuff provided huge list of qualifications are met.
Comments like this are often followed by "why not just use ASME listed materials?"
I find theses answers to be very unsatisfactory, because

1) there is no discussion regarding the generation of ASME table parameters such as basic allowable stress vs temp.​

2) in all my 13 years in the offshore industry every Client (including large oil majors) has required the use of API-5L pipe, ASTM A694 flanges and ASME VIII.
This combination of materials and code seems to be standard. Anyone saying they will use a different material or code raises red flags. 5L pipe, A694 flanges and ASME are the basics.​

So, there must be an easy standard way for using these materials with the ASME code.
Granted, for most of my career I have dealt with offshore structural analysis and left the ASME stuff to others.
But now that I have been getting more involved in piping/pressure vessls, I find this to be very disturbing. I am not sure how to complete some projects without resolution on this.
I have been looking through old archived project design reports (from my company and stuff shared from others in the course of collaborative work) and I find that this issues is never addressed. Many reports spanning 15+ companies just say they use API-5L as some part of a pressure vessel (usually the shell or saddle for a support) and evaluate to ASME VIII without ever reconciling the fact the 5L is not listed in the VIII. Many designs use A105 flanges in some locations, but A694 are common..again never addressing that A694 is not in ASME.
All of these designs have been reviewed and approved by a classification society and/or a major oil company without ever addressing this conflict.
I don't know how previous designers got away with this, but I NEED to know...and noone seems to have a satisfactory explanation.

 

[Gr8blu]

My understanding is this:
ASME Sect VIII refers to the construction of the pressure vessel - not the connecting piping.
ASME Sect II gives a list of ferrous materials - and their chemistry, mechanical properties, heat treatment methods, and manufacturability. Using something from A694 and/or API 5L would require comparing these properties ... not just the trade names of the ASME list.

Lastly, API tends to self-certify several things (including mechanical and electrical process construction) within the physical boundaries of petroleum and chemical facilities, in the belief that they have more and better knowledge of what is required than the general public. Is this true? In some instances yes, in other instances maybe not.

As to how the older stuff (and now the newer stuff) gets approved? "If it ain't broke, don't fix it."

Converting energy to motion for more than half a century

 

[LittleInch]

ASME B 31.4/8 etc lists MSS-SP-44 as a certified standard to use with pipeline materials such as e.g. API 5L X65

MSS-SP-44 is dimensionally the same as ASME B 16.5

Two massive advantages of MSS SP 44.

It's P-T table doesn't start de-rating until 121C (250F)
It allows A694 as a material (yeh)

Even B31.3 lists A694 in their materials specs so it's all good for them to use it. Then just use MSS-SP-44 as the material spec as this is also listed as a listed standard in table 326.1

I do agree many many people don't pick this up and just quote ASME B16.5 as the flange code when they shouldn't.

It's all about the boundaries with what is a pressure vessel and what is piping. Pipe is not normally part of a pressure vessel.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[KevinNZ]

Why specify API5L pipe for a pressure vessel part? Are you using trying to use one of the X grades?

 

[chris456s]

Thanks for the comments
@KevinNZ Using X52. "why use 5L for pressure vessel"....Large diameter 5L pipe is readily available.
Often already on site... no need to roll or form. Often seamless, so less welding.
Most of my projects are time driven rather than driven by the cost of design and materials. Saving a single day can make the client millions of dollars by starting a project sooner. The day rate on site development is huge and the so are the daily profit. So making a vessel from pipe with very thick flat heads instead of elliptical means far less fabrication time. The cost of thicker heads and pipe for shells is insignificant compared to the profit gained by getting the system into projection faster. So pipe is the goto option for vessels. No forming, no rolling. Just cut, weld and go.

@Gr8blu and others, thanks but I think you miss the point. 5L Pipe is often used for the shell of vessels (not just the connecting pipe work)and that material is not listed in the ASME VIII. For example, if a subsea buoyancy tank is needed (not a boiler, just a float for a hose or other sub-surface structure), it is common for people to cap the ends of a pipe and consider it a pressure vessel under external pressure.


Futher to this. Notice how VIII.1 referes to BPVC II Table 1A for Allowable Stresses but BPVC VIII.2 refer to BPVC II table 5A. Many materials (like A-53 and P235) are listed in table 1A but not on Table 5A or on BPVC VIII.2 table 3-A.1....So, what A-53 and P235 are suitable materials if you use methods in VIII.1 but not if you use methods in VIII.2....how does that make sense? What if there is a design that is ok using VIII.1 but you want to check it using FEA methods discussed VIII.2 Part 5, does it instantly fail because the materials are not listed for use on VIII.2 Table 3-A.1?

 

[LittleInch]

OK, I missed the point, but I think the fact that e.g. B31.3 gives values to use for stress gives you an ability to directly compare materials which are listed there but maybe not in ASME VIII

You may want to try looking in or asking a similar question in the boilers and pressure vessel forum where others may have come across this who don't participate in this forum. In general PV designers don't like using pipe for some reason so there might be some resistance there, but I totally understand your concern and issue.

What sort of size and pressure are we talking about here? Most pipeline material readily available wouldn't be more than 42" or maybe 60" at a push.

If you're welding thick flat plate instead of a hemi head then you're already at the practical end of the system - what sort of certification and AI do you use?

What does the AI say?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[weldstan]

One can use the API 5L unlisted materials in a PV if the PV is not subjuct to the Jurisdictional rules of ASME VIII or other Codes. You can use the basic design, testing and manufacturing parameters of ASME VIII or other Codes if one desires. If something disastrous happens to this type of vessel, liablity claims could be much higher than they would be if the vessel were to fully meet the Code requirement and be certified accordingly.